Reference : Excitation of the FUV Io tail on Jupiter: Characterization of the electron precipitation
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/7900
Excitation of the FUV Io tail on Jupiter: Characterization of the electron precipitation
English
Gérard, Jean-Claude mailto [Université de Liège - ULg > Département d'astrophys.]
Gustin, Jacques mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
Grodent, Denis mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP) >]
Delamere, P. [> > > >]
Clarke, J. T. [> > > >]
Nov-2002
Journal of Geophysical Research. Space Physics
Amer Geophysical Union
107
A11
Yes (verified by ORBi)
International
0148-0227
Washington
USA
[en] Io ; flux tube ; ultraviolet spectroscopy ; Jupiter ; electron energy ; slippage
[en] [1] Spectral observation of both polar regions of Jupiter in the far ultraviolet (FUV) obtained with the Space Telescope Imaging Spectrograph (STIS), on board the Hubble Space Telescope from July 1997 to January 2001 have been combined with FUV images to map the FUV color ratio along the STIS slit. Spatially resolved spectra of the aurora carried at similar to12 Angstrom resolution have been used to determine the amount of methane absorption as measured by the FUV color ratio of the Io magnetic footprint and its trailing tail. It is found that the absorption is systematically less than in the main polar aurora, indicating a higher altitude source region. The color ratio of the north tail is shown to slowly decrease downstream from the footprint. The combination of these spectral data with a two-stream model of the interaction of energetic electrons with the Jovian thermosphere indicates that the mean energy of the electrons creating the north FUV emission ranges from similar to55 keV at the Io footprint to similar to40 keV, 20 degrees downstream in the tail. In parallel, the incident electron energy flux drops by a factor similar to6 over the same angular distance. These observations are consistent with the steady state slippage picture where the subcorotating flux tube is accelerated very slowly up to corotation owing to the nonideal coupling. It is argued that small deviations from corotation can supply sufficient energy to fuel the observed auroral emissions. It is suggested that the parallel electric field accelerating electrons out of the flux tube only moderately depends on the time elapsed since the contact with Io, although the mapping between a point in the tail and Io is very uncertain in the presence of magnetic field line slippage.
http://hdl.handle.net/2268/7900

File(s) associated to this reference

Fulltext file(s):

FileCommentaryVersionSizeAccess
Restricted access
Io_tail.pdfNo commentaryPublisher postprint255.17 kBRequest copy

Bookmark and Share SFX Query

All documents in ORBi are protected by a user license.